Steerable monopole antenna system having a plurality of reflectors, said reflectors comprising a series of tubular vacuum switches



3,334,348 ITY OF NG A SERIES OF g- 1, 1967 w. A. ALFANO, JR

STEERABLE MONOPOLE ANTENNA SYSTEM HAVING A PLURAL REFLECTORS, SAIDREFLECTORS COMPRISI TUBULAR VACUUM SWITCHE Filed Nov. 25, 1966 4Sheets-Sheet l Attorney Aug. 1, 1967 w. A. ALFANO, JR 33 STEERABLEMONOPOLE ANTENNA SYSTEM HAVING A PLURALITY OF REFLECTORS SAID REFLECTORSCOMPRISING A SERIES OF CHES TUBULAR VACUUM SWIT 4 Sheets-Sheet 2 FiledNov. 25, 1966 INVENTOR. Hiam A. Alfano, Jr.

Attorney Aug. 1, 1967 w A. ALFANO, JR 3,334,348

STEERABLE MONOPOLE AI ITENNA SYSTEM HAVING A PLURALITY OF REFLECTORS,SAID REFLECTORS COMPRISING A SERIES OF TUBULAR VACUUM SWITCHES FiledNov. 25, 1966 4 Sheets-Sheet 3 INVENTOR. William A. Alfano, Jr.

wfQ/AM Attorney Aug. 1, 1967 W. A. ALFANO, JR 3,334,348 STEERABLEMONOPOLE ANTENNA SYSTEM HAVING A FLURALITY OF REFLECTORS SAID REFLECTORSCOMPRISING A SERIES OF TUBULAR VACUUM SWITCHES Filed Nov. 25, 1966 4Sheets-Sheet 4 Fig.7

Attorney United States Patent STEERABLE MONOPULE ANTENNA SYSTEM HAV- INCA PLURALITY OF REFLECTORS, SAlD RE- FLECTORS COMPRISING A SERIES OFTUBULAR VACUUM SWITCHES William A. Alfano, Jr., Los Altos, Calif.,assignor to Granger Associates, Palo Alto, Calif, a corporation ofCalifornia Filed Nov. 25, 1966, Ser. No. 596,944 4 Claims. (Cl. 343836)ABSTRACT OF THE DISCLOSURE A steerable, broadband high power antennasystem employing a monopole radiator surrounded by circularly disposedmutually spaced reflectors each comprising a plurality of verticallyaligned tubular metallic reflector sections having interposed vacuumswitches therebetween, said switches having pneumatic by-passesinterconnecting successive reflector sections, together withsolenoid-operated pneumatic valves selectively controlled to supplycompressed air to pre-selected reflectors to actuate desired vacuumswitches to closed position and effect changes in the steering and beamwidth of the radiated energy.

This invention relates generally to steerable antenna systems, and theinvention has reference more particularly to a broadband, high powersteerable antenna system that is capable of selectively directingelectromagnetic beams in a plurality of desired directions, the saidbeams being variable as to width to encompass variable areas at will.

This application is a continuation-in-part of my patent application Ser.No. 255,920 for Steerable Reflector Antenna System, filed Feb. 4, 1963,now abandoned.

Heretofore, where it has been desired to obtain a steerable or angularlyadjustable or movable radiation transmitting or receiving pattern, ithas generally been necessary to use a physically movable structure thatis complicated and expensive and ofttimes subject to large wind loadingsand having either radio frequency switching or coaxial rotary joints.Furthermore, these sweeping or steerable structures heretofore usedgenerally are limited as to frequency range, whereas the antenna systemof the present invention is so designed as to be employed for relativelywide-band use. Attempts have been made to employ directors andreflectors in combination to direct radio beams in a plurality ofdirections by using a combination of reflectors and directors, but suchdevices are extremely narrow band and not suitable for present-dayneeds. Also, these earlier devices encounter difliculty in attempting tobroadband the same because of difliculty in switching from director toreflector structures or from reflector to reflector structures.

It is therefore the principal object of the present invention to providea novel steerable antenna system employing preferably two broadbandmonopole radiators, one operating over a range of the order of four toeleven megacycles per second and the other operating over a range of theorder of eleven to thirty megacycles per second, said antenna systememploying a plurality of novel reflectors surrounding each monopole in acircular pattern, said reflectors comprising tubular members capable ofbeing electrically broken as to length through use of novel switchingmeans constituting a part of the tubular members structurally andactuated by pneumatic pressure.

A feature of the present invention is to provide a novel steerableantenna system of the above character wherein the number of effectivereflectors surrounding the antennae is selected from a transmittingstation through operation of solenoid valves controlling the flow of airto the tubular reflectors and effecting selective operation of thelatter.

Another feature of the present invention is to provide a novel steerableantenna system of the above character wherein means is provided foreliminating moisture from the air supplied to the reflector switchingmeans and for discharging air from the hollow reflectors into theconcentric feed line of the antenna, thereby maintaining the feed linealso free of moisture.

Another feature of the present invention is to provide a novel steerableantenna system of the above character wherein interlocking means isprovided for preventing energization of an antenna prior to desiredoperation of the reflector switches, thereby preventing possible injuryto the system.

These and other features and advantages of the present invention will bemore apparent after a perusal of the following specification taken inconnection with the accompanying drawings wherein:

FIG. 1 is a perspective view of the novel steerable antenna system ofthis invention;

FIG. 2 is a plan view of a portion of the structure shown in FIG. 1 andillustrates the manner of supplying pneumatic operating pressure to thevarious antenna reflectors for actuating the switching means and themanner of supplying electrical energy to the antennae themselves;

FIG. 3 is a view in elevation showing a reflector together with itssupporting structure;

FIG. 4 is a fragmentary enlarged view of a portion of FIG. 3 encompassedby arrows 4-4;

FIG. 5 is an enlarged sectional view taken along the line 5-5 of FIG. 3;

FIG. 6 is a plan view with parts broken away showing equipment includinga series of solenoid valves for controlling the operation of thereflector switches; and

FIG. 7 is an enlarged fragmentary view taken along the line 77 of FIG.6.

Similar characters of reference are used in the above figures todesignate corresponding parts.

Referring now to the drawings, the reference numeral 1 designates atransmitter building shown remote from two monopole radiators 2 and 3which are also spaced a suitable distance from each other. The monopole2 having a height of the order of fifty feet is of larger physicalproportions than monopole 3 having a height of the order of twenty feetand is a broadband antenna operating over a lower frequency rangepreferably of the order of four to eleven megacycles per second, whereasthe monopole 3 is intended to operate over a higher range preferably ofthe order of eleven to thirty megacycles per second. The monopoleantennae 2 and 3 are shown consisting of upper frusto-conical sections 4and 4, middle sections 5 and 5 of generally cylindrical shape, and lowersections 6 and 6' of inverted frusto-conical shape, these sectionsconsisting of a plurality of mutually spaced antenna wires suitablysupported by spreader rings to give the desired configuration andproviding omnidirectional radiation characteristics, the lower ends ofthe wires of monopole radiator 2 being electrically connected to theinner conductor of a concentric feed line 7, whereas the lower ends ofthe wires of the monopole radiator 3 are electrically connected to theinner conductor of a concentric feed line 7'.

The outer sheaths or conductors of concentric lines 7 and 7 areelectrically connected to conducting base plates 11, 11' that areinsulated from the antennae 2 and 3. Ground screens 26, 26' are providedfor antennae 2 and 3 and consist of radiating wires welded to plates 11and 11 at their inner ends and bonded at their outer ends to circularground wires 27, 27 that are grounded at intervals into the earth.Fences 58, 58 surround the antennae 2 and 3 to protect personnel againstinjury due to high antenna voltages. The concentric lines 7 and 7 areinterconnected intermediate antennae 2 and 3 by a coaxial switch 8 whichis adapted to connect either of these branch lines selectively to a mainsupply coaxial line 9 extending into transmitter building 1 forconnection to the transmitter 10 whereby either of the monopoleradiators 2 or 3 may be selectively energized from the transmitter 10.The selected monopole 2 or 3 is tuned to the frequency to be transmittedby means of adjustable impedance matching units 12 and 12 locatedadjacent the respective antennae, which units consist of inductors andcapacitors which are shunted across the concentric feed lines 7 and 7 atdiscreet points as required by vacuum switches controlled frompush-buttons mounted on a control panel 13 contained within thetransmitter building 1.

A pair of equipment housings 14 and 14' is located substantially midwaybetween antennae 2 and 3 and as shown in FIG. 6 each housing 14 and 14contains therewithin an enclosed compressor, dehydrator and tank unit 15which is connected to supply dehydrated compressed air through a pipe 16(see also FIG. 7), valve 17, filter 18, gauge 19, and pipe 20, to theinput of a series of dual solenoid-operated valves 21 connected intandem. The dual solenoid-operated valves 21 have similar valve portions22 and 23 on their opposite ends. Valve portions 22 are connected foropening and closing ports leading to a series of pipes 24, eight suchpipes being illustrated in FIG. 6 of the drawings, and similarly, thesolenoidoperated valve portions 23 are connected for opening and closingports leading to a series of pipes 24, eight such pipes also beingillustrated in FIG. 6 of the drawings.

It will be noted that within each of the housings 14 and 14' there aresixteen of these pipes 24 and 24' when combined, which pipes in the caseof housing 14 extend underground and to the vicinity of the monopoleradiator 2. As seen in FIG. 2, these pipes are so arranged as to extendrespectively adjacent to a series of vertical, preferably wooden, poles28 disposed in a circle around the antenna 2 and mutually spaced withrespect to each other, sixteen such poles being used in the drawings andillustrated in detail in FIGS. 3 to 5. The pipes 24 adjacent the poles28 are connected to vertically extending hollow reflectors 29 consistingof copper tubes or tube sections 29 which are supported from the poles28 by means of insulating brackets 30 having threaded stub shafts 31extending through apertures in the poles 28 and secured thereto as bynuts. The brackets 30 have pivotal bolt connections at 32 to permitthermal expansion and contraction of the hollow reflectors 29 in use byallowing these brackets 30 to swing up and down with respect to thepivotal points. The plurality of aligned tube sections 29 constituting areflector 29 are interconnected by tubular high vacuum switches 33, fivesuch switches evenly spaced along the reflector being shown for breakingthe reflector into short sections which are too short to act asreflectors throughout the frequency band of the antenna. However, whenthe vacuum switches 33 are closed (as will further appear), all thesections 29 of the tubing are interconnected electrically so that thesesections act jointly as a reflector, serving to reflect energy away fromthe supporting pole 28.

The vacuum switches 33 are shown in detail in FIG. 4, these switchescomprising a glazed ceramic, hollow, cylindrical housing 34 sealed atits ends to conducting tubes 35 and 36 as of copper, which tubes in turnare connected as by threaded nipples 37 and ferrules 38 to the coppertube sections 29'. The tube 36 carries a solid, cylindrical contactelement 39 sealed therein which ele ment projects downwardly into thehousing 34 for coopen ating with a similar contact element 40 that hasits upper end portion sealed to and supported upon the upper end of atubular, corrugated bellows 41 having its lower end sealed upon athreaded sleeve 42 that is threaded into the interior of tube 35. Thecylindrical contact element 40 has a loose fitting within a sleeve 43that is fixedly carried by the sleeve 42. A coil spring 44 surrounds thelower portion of contact element 40 and abuts at its upper end againstthe sleeve 42 and at its lower end against a washer 45 retained oncontact element 40 as by a pin. The bellows 41 permits upward movementof contact element 40 into contact with cooperating element 39 whenpneumatic pressure is supplied within the bellows, as will furtherappear; however, in the absence of proper pneumatic pressure, the spring44 urges the contact element 40 downwardly and out of engagement withthe contact element 39 as shown in FIG. 4.

It will be noted that, since pipes 24 and 24 are connected to thevertically extending reflectors 29, air under pressure supplied fromcompressor, dehydrator and tank unit 15 through solenoid valves 21 andpipes 24 or 24', as will further appear, will flow upwardly within thelowest reflector section 29 and hence upwardly between the lowestcontact element 40 and sleeve 43 to effect closure of the first vacuumswitch 33. Each vacuum switch is provided with a by-pass 47 comprisingelbow fittings 46 threaded into the tubes 35 and 36, the said elbowfittings being interconnected by insulating tubes 47 as of Teflon. Thus,when air under pressure is supplied to the lowest section 29 not onlydoes it serve to actuate the lowest vacuum switch 33 but such air willpass through the by-pass 47 on up to the remaining vacuum switches 33 insuccession to thereby electrically interconnect to tube sections 29 ofthe reflector, rendering this reflector 29 electrically continuous.

Similarly, the compressor, dehydrator and tank unit of housing 14'serves to supply dehydrated compressed air to solenoid-operated valves21 just as in the case of housing 14, which valves are connected throughcorresponding pipes 24 and 24' to reflectors 29' supported by poles 28'located in surrounding relation to the monopole radiator 3. The pipes ofthe compressor, dehydrator, and tank units of housings 14 and 14 arepreferably interconnected so that in the case of failure of one suchunit the other will take over the load in supplying air to thesolenoidoperated valves 21.

Thus, each monopole radiator 2 or 3 is surrounded by a set of sixteenvertical controllable reflectors which are equally spaced around acircle of proper diameter. By actuating all of the reflectors on oneside of the circle around the monopole 2 for example, a reflectingscreen is formed that concentrates the energy applied to the monopoleinto a directive beam. By actuating a smaller number of reflectors onone side of the circle, the beam is widened to the point where itprovides effective coverage over a larger area. Since the position ofthe group of active reflectors can be chosen at will from control panel13 by selectively energizing the valve portions 22 and 23 of the dualsolenoid valves 21 through leads 48 (FIG. 7), either of these types ofbeams could be steered at will to any of sixteen positions around thehousing. However, generally, the beam widths involved are such thateight discreet beam positions give adequate coverage at any givendirection, so that the system of the present invention provides beamsteerage to any of eight equally spaced azimuthal directions. Finally,by deactivating all of the reflectors 29, normal omni-directionalcoverage is obtained. Therefore, the system of the present inventionprovides seventeen different coverage modes in the azimuth planeanomnidirectional mode, eight wide coverage modes, and eight narrowcoverage modes.

It will be seen that, when the valve portions 22 and/ or 23 areenergized, compressed dry air supplied from the compressor, dehydratorand tank unit 15 will flow through pipe 16, through filter 18 and pipe20, to the series of solenoid-operated valves 21, so that the energizedvalve portions 22 and 23 will operate to allow such compressed air toenter pipes 24 and 24 as the case may be and flow to the selectedreflectors 29 at the desired poles 28. Pneumatic, electrical interlocks49 are shown connected to the pipes 24 and 24' and each in turn isconnected to the control panel 13 for preventing the supply ofelectrical energy to the desired antenna 2 or 3 until the air pressurewithin pipes 24 and 24 is suficient to ensure the operation of thevacuum switches 33 on the poles 28. Normally, the interlocks 49 are setto operate at 35 p.s.i. although the vacuum switches are capable ofoperating at as low a pressure as 20# psi. When it is desired todeactivate a reflector or reflectors 29, the proper button is pressed atthe control panel 13 which serves to de-energize the desiredsolenoidoperated valve portions 22 and 23 and this in turn allows thecompressed air in the pipes 24 and 24' to escape through ports 50 inthese valve portions so that springs 44 of the affected switches 33serve to open the latter, which escaping air maintains the pressure inthe housing 14, or 14 as the case may be, at around 5# psi. This air itwill be noted is clean and dehydrated, having passed through adehydrator and a filter, and is discharged through a pipe 51 having abranch with a relief valve 52 therein into a pipe 53 connected to thecoaxial lines 7, 7 9, thereby maintaining these coaxial lines at aslight pressure to exclude external air and maintain clean conditionstherewithin, any excess pressure escaping through relief valve 52. Pipe9 may also have a relief valve within the transmitter building 1 and mayeven be supplied with dehydrated air at that point should the same provedesirable.

It will be noted that the tubular pneumatic operated reflectors 29 areof extremely rugged and simple construction, the only moving parts beingthe vacuum switch contacts 40 and the bellows 41 which seals thesecontacts within the high vacuum of the switches. This constructioneliminates switch outer housings and the complexities of supplyingmechanical motion to each switch. Installation and maintenance aresimplified in that no critical alignment is required and the entirereflector consists of only two modular units, the switch module and thereflector tube.

Tests have shown that the novel antenna system of this invention has anoverall band width of from four to thirty megacycles per second and thecapacity to transmit 300 kW. average power with instantaneous peaks of1,200 kw.

Since many changes could be made in the above construction of the novelsteerable antenna system of this invention and many apparently widelydifferent embodiments of this invention could be made without departingfrom the scope thereof, it is intended that all matter contained in theabove description or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A steerable antenna system comprising a vertical monopole antenna, aconcentric line connected for energizing said antenna, a plurality ofmutually spaced poles surrounding said antenna, tubular reflectorscarried by said poles, said reflectors having a series of tubular vacuumswitches connected at regular intervals therein and structurally formingportions of said reflectors, said vacuum switches having pneumaticby-passes for passing air therearound, pipes connected respectively tosaid reflectors, a source of compressed air, solenoid-operated valvesconnected to said source for selectively connecting the same to saidpipes, and control means for selectively energizing saidsolenoid-operated valves to effect the operation thereof to supplycompressed air through said connected pipes to the desired reflectors,said compressed air in passing through said reflectors and through saidvacuum switch bypasses serving to actuate said vacuum switches insuccession to render said reflectors effective to direct radiant energyfrom said monopole antenna in a desired direction.

2. A steerable antenna system as defined in claim 1 wherein a secondvertical monopole antenna is positioned adjacent said first-namedantenna, a main supply concentric line, a second concentric lineconnected for energizing said second antenna, said second antenna havinga frequency band differing from that of said first-named antenna,coaxial switching means for connecting said main supply concentric lineto said first and second concentric lines for selectively energizingsaid antennae, said secondnamed antenna also having a series of mutuallyspaced poles arranged therearound, tubular reflectors carried by saidpoles, vacuum switches incorporated at regular intervals in saidreflectors, said vacuum switches having pneumatic by-passes for passingair therearound, additional pipes connected to said latter tubularreflectors, and additional solenoid operated valves connected to saidadditional pipes, said control means acting to selectively energize saidadditional solenoid operated valves for selectively energizing saidvacuum switches of said second-named antenna reflectors, said antennaebeing provided with ground screens comprising a plurality of angularlyspaced conductors radiating therefrom and connected to ground, saidfirst and second concentric lines having one of their sides connected toa respective ground screen and the other of their sides connected to arespective antenna.

3. A steerable antenna system as defined in claim 2 comprising a sealedhousing positioned intermediate said antennae and containing acompressor as said source of compressed air and also containing saidsolenoid operated valves, a dehydrator interposed between saidcompressor and said valves whereby only dry air is supplied to saidvalves and from thence through said pipes to said tubular reflectorsthereby preventing corrosion therewithin, and piping connecting theinterior of said housing to said coaxial lines, air exhaused by saidvalves from the pipes leading to said reflectors when the latter arede-energized serving to maintain a desired low internal dry air pressurein said housing and in the connecting concentric lines.

4. A steerable antenna system comprising a transmitter, a control paneladjacent said transmitter, a concentric line fed from said transmitterand having two branches, a pair of remote mutually spaced monopoleradiators fed respectively from said concentric line branches, saidradiators having diflering physical dimensions so together they cover awide frequency range, a plurality of mutually spaced poles surroundingeach of said antennae, tubular reflectors carried by said poles, saidreflectors having a series of tubular vacuum switches connected atregular intervals therein and structurally forming a part of saidreflectors, a housing intermediate said antennae, a compressor,dehydrator and solenoid actuated valves within said housing andconnected to be controlled from said control panel, pipes connectingsaid solenoid actuated valves to said respective tubular reflectors,whereby said solenoid actuated valves may be selectively controlled fromsaid control panel to activate desired reflectors to direct radiantenergy from said antennae in desired directions, and pressure responsiveinterlock switches connected to said pipes for preventing theenergization of said antennae in the event the air pressure within saidpipes is insuificient to properly operate said vacuum switches.

References Cited UNITED STATES PATENTS 1,860,123 5/1932 Yagi 323837 XR2,210,666 8/1940 Herzog 353-818 XR 3,244,842 4/1966 Kameyama et al.

HERMAN KARL SAALBACH, Primary Examiner. P. L. GENSLER, AssistantExaminer.

1. A STEERABLE ANTENNA SYSTEM COMPRISING A VERTICAL MONOPOLE ANTENNA, ACONCENTRIC LINE CONNECTED FOR ENERGIZING SAID ANTENNA, A PLURALITY OFMUTUALLY SPACED POLES SURROUNDING SAID ANTENNA, TUBULAR REFLECTORSCARRIED BY SAID POLES, SAID REFLECTORS HAVING A SERIES OF TUBULAR VACUUMSWITCHES CONNECTED AT REGULAR INTERVALS THEREIN AND STRUCTURALLY FORMINGPORTIONS OF SAID REFLECTORS, SAID VACUUM SWITCHES HAVING PNEUMATICBY-PASSES FOR PASSING AIR THEREAROUND, PIPES CONNECTED RESPECTIVELY TOSAID REFLECTORS, A SOURCE OF COMPRESSED AIR, SOLENOID-OPERATED VALVESCONNECTED TO SAID SOURCE, FOR SELECTIVELY CONNECTING THE SAME TO SAIDPIPES, AND CONTROL MEANS FOR SELECTIVELY ENERGIZING SAIDSOLENOID-OPERATED VALVES TO EFFECT THE OPERATION THEREOF TO SUPPLYCOMPRESSED AIR THROUGH SAID CONNECTED PIPES TO THE DESIRED REFLECTORS,SAID COMPRESSED AIR IN PASSING THROUGH SAID REFLECTORS AND THROUGH SAIDVACUUM SWITCH BYPASSES SERVING TO ACTUATE SAID VACUUM SWITCHES INSUCCESSION TO RENDER SAID REFLECTORS EFFECTIVE TO DIRECT RADIANT ENERGYFROM SAID MONOPOLE ANTENNA IN A DESIRED DIRECTION.